JPS60142339A - Method and apparatus for replenishing developing solution of photosensitive printing plate - Google Patents

Abstract

PURPOSE:To securely replenish a developing soln. without any time delay and to enable its activity to be kept in the allowable range by detecting pH of the developing soln., actuating an electrically drivable valve to replenish the developing soln. so as to maintain pH of the soln. at a preset value. CONSTITUTION:A photosensitive printing plate is imagewise exposed and developed with a developing soln. 3 in the developing soln. bath 2 of an automatic developing device 1, resulting in lowering of the activity of the soln. 3 and rise of its pH measured with the pH meter 8 of a developing soln. replenishment mechanism A as the change of the electromotive force of its electrode 10. The detected pH value is compared with the reference value preset in the meter 8, and the comparison result is fed to a regulator 9. When the pH value is below the prescribed value, the regulator drives an electrically drivable valve 7 to supply the bath 2 with the replenishing developing soln. 6 from its tank 5. When the pH of the soln. 3 is restored to the prescribed value, the regulator 9 stops the pump 7, thus ending the replenishment. As a result, lowering of the activity of the soln. 3 is prevented, and the activity can be maintained always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention relates to a developer replenishment method and apparatus for keeping constant the activity of a processing solution, particularly a developer for processing photosensitive printing plate materials. .

(Prior art) Conventionally, photosensitive printing plate materials include letterpress, flat plate, intaglio,
Although various types of printing plates are used, including stencils, etc., due to the ease of plate making, photosensitive lithographic printing plates have a support coated with a photosensitive liquid such as a photosensitive resin, and others coated with silver halide. Those that use electronic photolithography and those that perform electrophotographic engraving are widely used. These photosensitive lithographic printing plates include positive-working photosensitive lithographic printing plates and negative-working photosensitive lithographic printing plates. For example, positive-working photosensitive lithographic printing plates have a composition containing an O-quinone panazide compound on a support. Some devices are provided with a photosensitive layer containing a substance.

By the way, when the 0-quinone diabado compound is irradiated with actinic rays, it decomposes and becomes a compound having a carboxyl group. Therefore, when the photosensitive layer of a positive-working photosensitive lithographic printing plate containing an 0-quinone shea-cyto compound is exposed to actinic rays through a transparency, the 0-quinone diazide compound present in the exposed area is converted to carboxylic acid (1), and then alkaline development The solubility increases with the liquid, and a positive image is formed when developed.

In addition, negative photosensitive lithographic printing plates have a photosensitive layer on the support.
'Containing an azo compound, having a cisonamoyl group and t-
Various types of compounds are used, such as those containing compounds and those containing ethyl-1/one-based unsaturated hydrocarbons.
A negative image is formed by creating a network structure, etc., and by utilizing the difference in solubility between the two, and insolubilization. In particular, negative-working photosensitive lithographic printing plates containing photosensitive diazo compounds include, for example, No.
By mixing or combining a compound with an acid group such as luponic acid, solubility in an alkaline developer is imparted (1), and negative images can be obtained, and these are often used.

As described above, by developing with an alkaline developer, compounds having carboxylic acid groups dissolved in the developer and other acid components contained in the photosensitive layer are dissolved from the air. Carbon dioxide gas etc. neutralizes the alkaline components in the developer 2 and consumes them. In other words, by developing a photosensitive material containing a photoconductor having an alkali-soluble component or a photoconductor having an alkali rJf-soluble component, the alkaline component in the developer is reduced.

When the activity of the developer decreases due to a decrease in the alkaline component in the developer, and the developing ability becomes insufficient,
In addition to preparing new developer and replacing the entire amount,
Conventionally, a method has been used to restore the developing activity of the developer by replenishing the decreased alkaline component of the developer.

One method for replenishing this developer is to process a certain printing plate, calculate the composition and amount of alkaline components necessary to recover the resulting decrease in development activity, and process the printing plate. It has been practiced to replenish developer replenisher in an amount corresponding to the area to be processed each time, or in proportion to the length of one side of the printing plate, or in a required amount at regular intervals. These are disclosed in JP-A-50-144502 and JP-A-55-115039.

However, the decrease in developer activity due to printing plate development, especially the consumption of alkaline components, is not only due to the area of the printing plate being developed, but also because the resin image is dissolved within the developing printing plate. Things related to the photoreceptor, such as the area ratio of non-image areas (non-image ratio), the acid value of the photoreceptor to be dissolved and developed (the amount of alkali required to neutralize the acid groups contained in a unit photoreceptor), and processing equipment. , its shape, the state of contact between the developer and the air, the duration of the development process, the partial pressure of carbon dielectric in the air, and other factors.

Therefore, in the conventional method, the replenishment work is very troublesome.
It takes a lot of work to put in the necessary amount of paper in proportion to the length of the sides of the printing plate, and to put in the necessary amount at regular intervals.1. When replenishing an amount proportional to the length of one side of the printing plate, not only will there be a difference in area due to the length in the perpendicular direction, but even if replenishment is performed for the corresponding area, Also, the amount of replenishment varies depending on the non-image rate of the exposed printing plate.

Furthermore, because of different uses, different types of printing plates are often mixed and processed in the same processing equipment. In this case, printing plates with photoreceptors with different alkali loads (acid values of photoreceptors) are mixed. The amount of replenishment required to restore the developer's activity is complicated and varied.
The situation becomes even more difficult. In other words, since this method does not directly determine the activity of the processing solution and replenish it accordingly, there is a risk that the activity may deviate from the permissible range.

In addition, as a replenishment of Lj developer, Utility Model No. 52-33329
As shown in the above publication, it is known to operate a pH control device using a solenoid valve to replenish the replenisher. 6
However, if there is a sign of a decrease in activity due to fatigue of the developer, it may take time for the activity to recover, or it may become over-replenished and fall outside of the allowable range, resulting in a slow response in the sense of so-called control engineering. It may cause vibration. In this case as well, the desired printing performance cannot be stably obtained, and it has been generally believed that sufficient replenishment cannot be achieved by managing the developer using pH.

When developed with a developer whose development activity is outside the permissible range as described above, the expensive photosensitive printing plate is damaged and wasted. In addition, it is important for those skilled in the art to always maintain the activity of the developer within a predetermined tolerance range, but it is extremely troublesome and technically difficult. The amount of developer replenishment is automatically determined based on the pH of the developer, eliminating the need for determining the amount of developer replenishment. It is an object of the present invention to provide a method and an apparatus for developing and replenishing a photosensitive printing plate, in which replenishment of a replenishing developer is carried out according to the displacement from the surface of the photosensitive printing plate, and the activity of the developer is always maintained within a predetermined tolerance range.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention provides a method for replenishing development of a photosensitive printing plate according to the first invention, in which a developing solution is used when an image-exposed photosensitive printing plate is developed in an automatic developing device. It is characterized by detecting the pH and replenishing the developer replenisher by operating an electric valve of the developer replenisher tank so that the activity of the developer is maintained within a predetermined range. Further, the development replenishment device for a photosensitive printing plate according to the second invention includes a pH meter for detecting the pH of the developer, and a pH meter for detecting the pH of the developer.
i(), and includes a controller that outputs an output when the pH deviates from the set value, and an electric valve that is provided in the developer replenisher tank and opens and closes according to the output of the controller.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a developing device for a photosensitive printing plate according to the present invention;
FIG. 2 is a diagram showing the state of management of developer activity.

In FIG. 1, reference numeral 1 denotes an automatic developing device, and this automatic developing device 1 is equipped with a developer tank 2. As shown in FIG. The developer tank 2 is filled with a developer 3 for photosensitive printing plates, and this developer 3 is circulated by a circulation pump 4.

A developer replenisher tank 5 is provided adjacent to the developer tank 2, and the replenisher '6 filled in the developer replenisher tank 5 is replenished into the developer tank 2 by an electric valve 7.

The automatic developing device 1 is equipped with a pH meter 8 and a controller 9.
The electric valve 7 is operated to maintain the pH (hydrogen ion concentration) of the developer 3 at a predetermined value, and the developer tank 2 is replenished with the replenisher 6 from the developer replenisher tank 5.

The p)I meter 8 has an electrode 10 for pH detection, and this electrode 10 is composed of an indicator electrode 10a and a comparison electrode 10b. The indicator electrode lOa and the comparison electrode 10b are provided in the developer tank 2 and are always in contact with the developer 3. Then, the pH of the developer 3 is measured by the electromotive force generated between the indicator electrode 10a and the comparison electrode 10b, and when the developer 3 is exhausted and the pH falls below the set value, p) I total 8 is the electromotive force. is transmitted to the controller 9.

Examples of the indicator type Fjl Oa include a glass electrode and an antimony electrode.An antimony electrode is preferable because it is robust, but a glass electrode is more preferable because it allows highly accurate measurement. The glass electrode has an internal electrode inside the main body,
A calomel electrode or a silver chloride electrode is preferable as this internal electrode, and a silver chloride electrode is more preferable because of its small temperature hysteresis.

The reference electrode tob may be a standard hydrogen electrode, a calomel electrode, a thallium chloride electrode, a silver chloride electrode, a solid reference electrode, or the like. This calomel electrode, thallium chloride electrode, silver chloride electrode,
Solid-state comparison electrodes are preferred because they are easy to use, and among them, calomel electrodes, silver chloride electrodes, and solid-state comparison electrodes are preferred because they are easily available and allow stable measurements. As for the chemical substances used in the electrode, silver chloride electrodes are more preferable due to their safety (silver chloride electrodes are more preferable due to their safety), and silver chloride solid reference electrodes using gel containing Kcl and Agc1 (saturation is best) reduce the frequency of maintenance and inspection required. It is most preferably used because of its low

Furthermore, in addition to these electrodes, it is desirable to use a temperature compensation electrode for correcting electromotive force due to temperature changes of the electrodes.

The controller 9 is connected to a pH meter 8, and is configured to actuate the electric valve 7 when an electromotive force greater than a set value is generated in the pH meter 8. The controller 9 includes 2-position type, 3-position type, proportional position type, on-off pulse type, on-off pulse type, electric thorn output type, etc. The electric valve 7 includes one for on/off operation, one with a servo mechanism, and the like.

The electrode 10. The pH meter 8 and the controller 9 are electrically connected. Then, the oil pressure from the controller 9,
The valve 15 generates fluid pressure such as water pressure or air pressure, or generates electromagnetic waves such as sound waves, electricity, or light, and the output thereof is applied to the electric valve 7 to drive it.

It should be noted that this adjustment is advantageous in that the H and pH types can be integrated, which allows for the simplification of the apparatus.

Next, in 4.7, the operation of this embodiment will be explained.

A photosensitive printing plate is exposed to light in both images 1 and developed with a developer 3 in a developer tank 2 of an automatic developing device 1. This development reduces the activity of the developer 3 and lowers the pH value.

This decrease in the pH of the developer 3 causes the pi-
is detected as a change in electromotive force. Then, te, p
It is compared with the set value set in Ha18, and the comparison result is output to the controller 9.

When the pH value is below a predetermined set value, the controller 9 drives the electric valve 7, and the developer replenisher 6 is transferred from the developer replenisher tank 5 to the developer tank. will be replenished to. Then, when the pH of the developer 3 returns to the set value, the controller 9 via the pH meter 8 stops driving the electric valve 7 . This completes the replenishment 2 and prevents the activity of the developer 3 from decreasing and keeps it constant.

The electric valve 7 operates in response to the output from the controller 9, and even if the activity of the developer is severely reduced,
No time is required to secure a predetermined flow rate at the initial stage of operation. Also, there will be no vibration due to liquid pressure when the valve is open, or a delay in operation when the valve is closed. Over-replenishment will not occur.

In this more specific embodiment, Sakura (registered trademark) PS plate developer is installed in the developer tank 2 of an automatic developer for photosensitive planographic printing plates PSA-860A (manufactured by Konishiroku Photo Industry Co., Ltd.) as an automatic developer 1. Pour 12 liters of the specified diluted solution of 5DR-1 (manufactured by the company) 3. A glass electrode (
silver chloride inner electrode), silver chloride reference electrode, and temperature compensation electrode.
Connect each lead wire to pH meter 8 5, and from there to controller 9.
Connected to. Then, the activity of developer 3 decreases and the pH
The controller 9 is set so that the developer replenisher 6 is replenished when the value drops to 12.5. Sakura PS version developer 5DR-
Fill the developer replenisher tank 5 with the specified diluted solution (manufactured by IRC), and install the electric JT 7 on the replenishment path to the developer tank 2.
This electric valve 7 and controller 9 were electrically connected.

Figure 2 shows the control chart of development activity according to this specific example.
-I am.

Two types of photosensitive printing plates with an area of about 0.7 m', Sakura PS plate SMP 76- and ST, pC Konishi: <manufactured by Shani Kogyo Co., Ltd.) were used together with halftone transparencies.
Bring the step doublet and Brunner manuscript into close contact. Then, exposure was carried out for 75 seconds from a distance of 0.8 m using a metal halide lamp (manufactured by Iwasaki Electric Co., Ltd., Idol Fin 2000), and the measurement results were obtained by performing a development operation intermittently for 4[1] periods at a throughput of 45 plates per day. showing and being. In order to know the subtle level of development activity, the number of solid steps in the step tablet portion after development and the visible percentage of minimum dots in the Ifflner original are managed.

Figure 2 Ca) shows the measurement results of this example,
The number of solid steps of the step tab 1-771 portion and the minimum point reproduction percentage of the Brunner thick manuscript are both within the J1 volume range. For this reason, the desired printed matter can be obtained from the obtained printing plate, and the replenishment liquid 6 is refilled at a flow rate of Iff, L, which corresponds to the displacement from the permissible range without any time delay due to the drive of the electric valve 7. and responds quickly, especially at the start of operation.

Further, the recovery from the decrease in activity during nighttime stoppage is quick, and stable developing activity can be maintained thereafter.

FIG. 2(b) shows a similar developing operation in which the electric valve 7 of this embodiment was replaced with a solenoid valve.

This requires a predetermined time to recover the activity at the time of night stoppage 1 and then replenishment, resulting in an unacceptable development activity 1 and requiring a long time to reach the desired development activity. And, during this time, the photosensitive printing plates are wasted.

FIG. 2(c) shows a replenishing device of the type in which the developer replenishment mechanism of this embodiment is not provided, and the developer is automatically replenished each time one plate is processed using a microswitch, similar to the previous embodiment. Shows the results of developing operation.

ing.

This is due to the fact that the E1 processing space and the type of photosensitive printing plates used are uneven, even though the activity was restored every day by adding replenisher at startup to compensate for the decrease in activity during nighttime shutdown. Depending on various conditions, the development activity often falls outside of the allowable range, resulting in a printing plate that is prone to printing smudges or not achieving the desired halftone reproducibility, which can result in wasted photosensitive printing plates. .

(Effects of the Invention) As described above, this invention detects the pH of the developer when an image-exposed photosensitive printing plate is developed in an automatic processor, and maintains the pH of the developer at a set value. The motorized valve is operated to replenish the developer replenisher, and the developer replenisher is refilled by detecting the liquid properties, eliminating the need for work such as determining the amount of replenishment, making it easy to replenish the developer. And it becomes certain. Since replenishment of the developer is performed by an electric valve, the response of the developer is better than that of a conventional solenoid valve, and vibrations are reduced, so that the developer is refilled without any time delay. The activity of the fluid can be refilled more reliably without exceeding the permissible range.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a developing device for a photosensitive printing plate according to the present invention;
FIG. 2 is a diagram showing the state of management of developer activity. ■...Automatic developing device 2...Developer tank 5...Developer replenisher tank 7...Electric valve 8...PH meter 9...
Controller 10...Electrode patent applicant Konishiroku Photo Industry Co., Ltd.

Claims (2)

[Claims] (1) When developing an image-exposed photosensitive printing plate using an automatic developing device, the pH of the developer is detected and the electric valve of the developer replenisher tank is activated to maintain the activity of the developer within a predetermined range. A method for replenishing development of a photosensitive printing plate by replenishing a developer replenisher. (2) A pH meter that detects the pH of the developer and this pi-1
Linked with meter 1. p) A developing and replenishing device for a photosensitive printing plate, comprising a controller that outputs an output when deviates from a set value, and an electric valve that is provided in a developer replenisher tank and opens and closes according to the output of the controller.